#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <assert.h>

char* my_strstr(const char* str1, const char* str2)
{
	assert(str1 && str2);
	const char* cp = str1;
	if (*str2 == '\0')
	{
		return ((char*)str1);
	}
	while (*cp)
	{
		const char* s1 = cp;
		const char* s2 = str2;
		while ((*s1 != '\0') && (*s2 != '\0') && (*s1 == *s2))
		{
			s1++;
			s2++;
		}
		if (*s2 == '\0')
		{
			return (char*)cp;
		}
		cp++;
	}
	return NULL;
}

int main()
{	
	char arr1[] = "hello bit!";
	char arr2[] = "lo";
	char* p = my_strstr(arr1, arr2);
	printf("%s", p);
	return 0;
}